Frequency changing system for high frequency signaling apparatus



Feb. 6, -1934. L. A. GEBHARD 1,945,525

FREQUENCY CHANGING SYSTEM FOR HIGH FREQUENCY- SIGNALING APPARATUS Filed Dec. 6. 1952 3 Sheets-Sheet vl 7 3@ l 51T i y y f A i 5 40 4f I LQ'l v lY 4 A .-4 f 9 4 A 4f i fa a 44 gi ff y 1;1 fi, 1 9@ 2925/ gg, @y 20' f 45 2/ 22' l 2f 47 /5 155' l i 36u 52' i 4 /5 '54, 55 59' /9' 5a a, v

l a 2 '/f /K f //4 U- d lU //f l; T

r// a: .Q i

f l l L ZL- AA "S-M 6 INVENTOR Eef.. a f4 /g g 04410 el. Swfzaw,

Y L l, A We; ATTORNEY.'

Feb. 6, 1934. L AqGEBl-IARD 1,945,525 K v FREQUENCY CHANGING SYSTEM FOR HIGH FREQUENCY SIGNALING APPARATUS l Filed Dec. 6. 1932 s sheets-Sheet 2 1 Tri-r1.. E'. K f *T- IN VEN TOR.

mgm,

com @u ATTORNEY L. A.' GEBHARD Feb. 6, 1934. FREQUENCY CHANGING sYsTEM ECR HIGH FREQUENCY SICNALING APARA'rUs Filed Dec. 6. 1952 -3 Sheets-Sheet '3 INVENTCR & /wa M ATTORNEY.

E l. v zi Patented Feb..6, 1934 UNITED STA FREQUENCY CHANGING. SYSTEM FOR HIGH FREQUENCY' SIGNALING APPARATUS Louis A. Gebhard, Washington, D. C. Application December (i, 1932. Serial No. l645,961

(Granted under thc`act-of March 3, 1883, 'as amended April 30, 1928;Y 37.0 O. G. 7.57)

14 Claims.

My invention relates broadly to high frequency transmitters andmore particularly to frequency adjusting means for highv frequency signaling systems. Y

5 One of the objects ofmy invention is'to provide an improved construction of frequency changing apparatus for high frequency signaling systems by which rapid change in the operating frequency may be effected and high efficiency in the signaling apparatus obtained.

Another object of my invention is to provide a construction of magnetically and electrically shielded frequency changing apparatus for high frequency signaling systems in which changes in frequency mayy be rapidly eiectedwhile maintaining a high degree of efficiency in thesignaling apparatus.

Still another object of my invention is to provide a compact construction of frequency changing apparatus for high frequency signaling systems in which inductance coils of selected frequency characteristics are mounted on a stationary frame structure adjacent a switching mechanism for completing connection between select- .ed inductance units and associated oscillation cir-- cuits with a minimum length of leads for avoiding` losses and maintaining a high degree of eiliciency in the signaling system.

A further object of my invention is to provide a construction of electrically shielded drum enclosing a multiplicity ofinductance units of different frequency characteristics with means for electrically shielding adjacent inductance units with switching means coacting with the inductance units for establishing electrical connection between a selected inductance unit and associated oscillation circuitstwhile maintaining a high degree of efficiency in the operation of the signaling apparatus. f

A still further object of my invention is to provide a construction of signaling apparatus in which a. switching system is mounted for rotative adjustment man annular path ywithin a multiplicity of inductance units of different frequency characteristics for establishing electrical connection between an oscillation circuit and a selected inductance unit, the inductance units being electrically and magnetically shielded for obtaining maximum efficiency in the operation of the signaling apparatus. A

Another object of my invention is to provide a construction of electrically shielded drum forming mounting means forV a multiplicity of inductance units of different frequency characteristics, the inductance units being disposed lin a path kfrequency signaling system as set forth more fully in the specification hereinafter following by refc5 erence to the accompanying drawings, in which: Figure l is a longitudinal sectional view taken on line 1-1 of Fig. 2; Fig. 2 is a transverse, vertical sectional view taken on line 2-2 of Fig. 1; Fig. 3 is a similar view taken on line 3-3 vof Fig. 70

.1; Fig. 4 is a horizontal sectional view taken on Aline 4-4 of Fig. 3;`Fig 5 is a fragmentary front elevation of a portion o f the casing; Fig. 6 is a detailed sectional view showing more particularly.

-the arrangement of the contact brushes; Fig. 7 is 75 a fragmentary sectional view on line '1 -'7 of 4', showing the means employed to stop the rotation of the inner shell; Fig. 8 is a fragmentary side elevation over a portion of the shell lretaining ring; and Fig. 9 is a detailed vertical sectional 3 view taken on line 9--9 of Fig. 8. One of the difficulties met with in a transmitter having a widev frequency band is due to the coupling, both electric and magnetic, between the coils used for different frequency ranges -85 that are part of the input and output circuits of the amplifiers. Generally, butone coilv is used at a time, but other coils must be available and must be placed in close proximity to the coil in use in order that the transmitter may be compact and in order that the length- ,of the necessary leads are not so -excessive as to prohibit'operation at high frequencies. Of course, the coils may be of the plug-in type, in which case but one coil is in use in the transmitter .at one time, the other coils being kept about the radio room adjacent the transmitter. This is an unsatisfactory arrangement, it being far more desirable to incorporate the coils in the transmitter and provide a switching system to substitute quickly one coil foranother in the*- circuit. Quick interchange is impossible with- ,L

shielding results in that there is a certain amount y as a result of this capacity, considerable energy may be transferred from a coil in use to one which is not in use. The system shown. in the accompanying figures is arranged to reduce Vthis electric coupling to a minimum. Adequate magnetic shielding is also provided in this system. The system also provides a number of unique constructional features.

The coils are shown at 1 mounted in a circular arrangement. These coils are of different frequency characteristics and instead of being a single coil may comprise several coils adjacent to each other or coaxial with each other. Each coil unit 1 is contained in a compartment formed by two concentric metcl cylinders 2 and 3. The ends of these cylinders are closed by means of annular metallic plates 4 and 4'. Partitions 5 extending radially divide the space into the required number of compartments. Any number of compartments or any Lumber of coils may be used. Members 5 are turned over at right angles at their outer edges as shown at 6 so as to permit fastening of the cylinder 2. They are also turned over at right angles at their outside edges as shown at 7 and 7' so as to permit fastening of the sides 4 and 4' to make the structure rigid. The outer cylinder 3 and through it the rest of the structure, is supported by angle members 8 and 8' from the framework on the radio transmitter shown at 9, 9', 10 and 10. The front panel of the high frequency transmitter is shown at 11, the rear panel at 11. Inner cylinder 2 is arranged to turn in bearings formed by theannular metallic plates 4 and 4. yRing members 12 and 12 serve to hold cylinder 3 in the bearings. The ring members 12 and 12 consist of rings made of iiexible metal material fastened to annular metallic plates 4 and 4 by means of screws 13. The inner peripheral edges of these rings are split as shown at 14 so as to provide good contact to the ends of cylinder 2, thus completing the connection of the shielding and providing effective means of shielding. The ends of cylinder 2 are closed off by members 15 and 15. Members 15 and 15' are fastened to cylinder 2 by means of screws 2a extending through cylinder 2 and into the edges of members 15 and 15. At the centers of members 15 and 15 there is mounted a shaft 16 by means of bearing members 17 and 17' which are secured to the shaft by means of pins 18 and 18'. Bearing 'members 17 and 17 are fastened to members 15 and 15' by means of screws 17a and 18a. Members 15 and 15 are made of suitable insulating material and on their outer surface are mounted collector rings 19, 19', 20 and 20. These rings are secured to members 15 and 15'- by means of screws 15a and 15a. Connections are provided tothese rings at 21, 21', 22 and 22'. An insulating member 23 extends between end members 15 and 15'. The member 23 carries contacts 24 which pass through a narrow slot 25 in cylinder 2 engaging wlth the oppositely directed brushes 26 mounted on the inductance coils 1. Slot 25 does not extend over the full length of the cylinder but only between points 27 and 27. The electrostatic shields or compartment dividers 5 are provided with narrow slots as shown at 28 so as to permit passage of contacts 24 as the drum 2 is rotated for the selection of aninductance unit. These slots are very narrow but fully wide enough to permit the contacts 24 to pass through. It desired these slots may be arranged with a Ystatic coupling.

. 1,945,525 'of capacity between these coil contacts and mechanism which will close after the contact has passed through. Ordinarily, however, the slots are so narrow as to provide no serious amount of electric coupling between the adjacent coils. It will be noted that as cylinder 2 rotates, the slot 25 follows so that it is always in the position of the used coil, all other coils being effectively shielded from the coil in use.

Connections 29, 29', 30 and 30' are provided between the collector ring binding posts 2l, 2l', 22 and 22' and the binding posts 31 of contacts 24. Connection is made between collector rings 19, 19', 20 and 20 and the external circuit by means of brushes 32, 32', 33 and 33 mounted on insulating members 34, 34', which are supported by means of spacers 35 and 35', 36 and 36 on side members 4 and 4' by means of screws or bolt members. A stopping device or pawl 37 is mounted on insulating member 34 by means of screws or bolt members. This pawl or device 37 carries a tooth at the end of a flat spring member which engages with detents 38 in meinber 15. This stopping mechanism serves to arrest rotation of the cylinder in the proper positions to engage the coil contacts.

Binding posts 39 and 39 are provided for connections to the external oscillator circuits which are arranged immediately adjacent the frequency changing apparatus for avoiding losses inherent with long leads.

Coils 1 may be supported in their compartments in any desirable way. One method is shown by the use of insulating members 40 and 4l disposed at right angles to each other and sccured by screws 42 between the metallic plates 4 and 4. The coils 1 are spaced from the walls forming the compartments. It will be observed that the compartments are closed on the six sides thereof by `metallic walls which serve to electrically and magnetically shield each of the inductance units from each other and from the influence of external electrostatic or electromagnetic fields. The metallic enclosures within which each of the inductance units are mounted serve to confine the electrostatic and electromagnetic fields of each'inductance unit to the individual compartments thereby enabling the apparatus to be compactly assembled without causing mutual electrostatic or electromagnetic interference and without becoming a source of undesired and interfering electromagnetic or electrostatic fields. The shaft 16 is caused to rotate by means of control 43 located on the front of the front panel. The dial 44 indicates the particular coil in the circuit bynumerals engraved on the surface as shown at 45 which can be seen through aperture 46 in the front panel 1l. The coil contacts may consist of brushes 47, 47' fastened to a member 48 by means of screws 49, 49'. Member 48 is fastened tothe turn of the inductance coil in a predetermined position by soldering or other means.

It will be understoodthat many modifications in the structure of my invention may be made. For instance, the brushes 26 instead of being mounted on the coil may be mounted on the moving member and the contacts mounted on the inductance coil. This arrangement is in general undesirable, however, due to the fact that the slots 28 can be made narrower if the brushes are placed on the coil and the contacts allowed to rotate thereby avoiding losses due to electro- The brushes 26 need not be mounted directly on the coil but can be mounted on an insulating member supported in any desirable way but independent from the coil. The

liti' 'and movable within said metallic housing, and

coil itself may take any form desired and may be a series of windings or a single winding. The

insulating strip supporting the contacts 24 .re-l

ferred to may also be mounted on 'the coil if de- 5 sired. Another modification lmay be made by vention regardless oi the fact thatv rapid change of the selected inductance units may be made.

The metallic rotatable cylinder 2 establishes electrical connection with the edges of the annular metallic plates 4 and 4. As the cylinder 2 rotates-the continuity of the metallic shielding on all four sides of the inductance coil is maintained as electrical connection is made at all times with the edges of radially extending shields 5 at the Sametime that cylinder 2 makes electrical connection with the edges of annular metallic plates 4 and 4. Extremely short connec` tions are made to the adjacent oscillation circuits. While I have indicated such connections schematically as wired elements, it is understood that such connections are in the form of busses of relatively large surface area having low resistance to radio frequency currents.

I have described my invention in certain preferred embodiments, but Il desire that it be un'- -derstood that modications may bemade by those skilled in the art and that no limitations upon my invention are intended other than are imposed by the scope of the appended claims.

The invention described herein may be manufactured and used by or for the Goverment of the United States of america for governmental purposes without the payment of any royalty thereon or therefor.

`What l claim as new and desire to secure bv Letters Patent of the United States is as follows:

l. In a frequency changing apparatus, a sup- -porting structure, a metallic housing carried by said supporting structure, applurality of electrically shielded metallic compartments formed in said housing, insulated supports in each of said compartments, inductance yunits of diiferent Irequency characteristics carried by said supports and having taps thereon, said inductance units being spaced from `the L-wallsof said metallic compartments, a rotatable metallic cylinder disposed concentrically within said metallic housing, conv`tact members extendingthrough apertures formed in'said rotatable cylinder for establishing `connection with selected taps on said inductance units, and means for angularly shifting said cylinder for correspondingly establishing connection with a selected inductance unit.

2. In a frequency changing apparatus, a supporting structure, a metallic housing Icarried by said supporting structure, a multiplicity of radially disposed compartments in said metallic housing, inductance units of different frequency characteristics mounted in said compartments and spaced from the walls of saidcompartments, a rotatable Ametallic cylinder forming the inner wall of said compartments and concentrically disposed with respect to saidmetallic housing switching means carried by said rotatable metallic cylinder for establishing connections with selected inductance units.

3. In a frequency changing apparatus, a supporting frame, a metallic housing carried by said supporting frame, a multiplicity of electrostatically shielded compartments disposed radially with respect to said metallic housing, insulated supports extending through each of said cognpartments, inductance units of different frequency characteristics carried by the supports inA said compartments, a cylindrical metallic shield forming theinner wall of said metallic housing, contact members projecting through said cylindrical metallic shield, and means for rotatably movingsaid shield for establishing elec-A trical connections between' said contacts, and i taps on selected inductance units in said compartments.

4. Frequency changing apparatus comprising a frame structure, a metallic housing carried by said frame structure, a multiplicity of radially disposed electrostatically shielded compartments in said housing, inductance units of different frequency characteristics mounted in said compartments, a cylindrical electrostatic .shield forming the inner wall of said housing, bearings for mounting said cylindrical electrostatic shield for rotative movement within said housing, ar actuator for imparting angular movement to said cylindrical electrostatic shield,e and a multiplicity of contact membersr projecting through said cylindrical electrostatic shield for establishing connection with selected inductance units in` said compartments as said actuator is rotated.

5. In a frequency changing apparatus, a supporting structure, a metallic housing carried by said supporting structure, a multiplicity of radially disposed atplate members constituting .for establishing connection between said switching means with selected inductance units in said compartments.

6. In a frequency changing apparatus, a supporting structure, a metallic housing carried by said supporting structure, said housing being constituted by a substantially toroidal shaped electrostatically shielded container, a cylindrical member forming the inner wall of said toroidal container, electrostatically shielded compartments disposed in said toroidal container, inductance units of dierent frequency characteristics in each of said compartments, and switch elements projecting through said cylindrical member for establishing electrical connection with selected inductance units, and means for angularly adjusting'the position of said switch elements for correspondingly selecting vthe inductance units.

'7.fIn a frequency changing apparatus, a cylindrical metallic housing, a frame structure sup- Lit liz)

trostatically shielded compartments, inductance units of different frequencyfcharacteristics disposed in each of saidcompartments and spaced from the walls thereof, switching means projecting `ythrough said cylindrical member and insulated therefrom for establishing electrical connection with a selected inductance unit, and means for rotatably adjusting the position of said cylindrical member for correspondingly establishing connection between said switching means and a selected inductanoe unit.

8. Frequency changing apparatus comprising a supporting structure, a toroidal metallic chamber carried by said supporting structure, a rotatable member having a cylindrical wall forming the inner closure for said toroidal chamber,

`electrostatic shields extending radially of said toroidal chamber and forming electrostatically shielded compartments within said toroidal chamber, inductance units of different frequency characteristics mounted in each of said compartments, switching means extending through said cylindrical wall for establishing connection with a selected inductance unit, and means for shifting said switching means to a selected nductance unit while maintaining the electrostatic isolation of inductance units.

9. In a frequency changing apparatus, a supporting structure, a metallic casing carried by said supporting structure, a plurality of inductance units of different frequency characteristics mounted interiorly of said metallic casing and spaced from the wall formed by' said casing, a cylindrical member constituting the inside Wall of said casing, means for journaling said cylindrical member for rotation with respect to said casing, and switching means extending through said cylindrical member and insulated therefrom for establishing selective electrical connection with a selected inductance unit within said cham ber.

l0. In a frequency changing apparatus, a supporting structure, a metallic casing carried by said supporting structure, a plurality of inductance units of different frequency characteristics mounted interiorly of said metallic casing in spaced relation to the wall of said casing, a cylindrical member constituting the inside wall of said casing, an insulated end wall closing each end of said cylindrical member, collector rings mounted on said end walls, contact members extending through said cylindrical member and electrically insulated therefrom for establishing connection with a selected inductance unit, connections between said contact members and said collector rings, and means passing through said end walls for moving said contact members for establishing connection with a selected inducltance unit.

1l. In a frequency changing apparatus, a' supporting structure, a metallic casing carried by said supporting structure, a plurality of inductance units of different frequency characterise tics mounted interiorly of said metallic casing and spaced from the wall of said casing, a cylin drical member constituting the inside wall of said casing, an annular plate connected to each end of said casing and extending across the pe ripheral edge of sa-id cylindrical member for rotatably journaling said cylindrical member within said casing, an insulated end plate disposed laterally across each end of said cylindrical member, collector rings carried by said insulated end plates, contacts electrically connected with said colle @tor rings and projecting laterally through one side of said cylindrical member and electrically insulated therefrom for establishing selective connection with said inductance units, and means connected with said insulated end plates for imparting angular movement to said cylindrical member :for correspondingly shifting said contacts for renderingselected inductance units electrically effective.

l2. Frequency changing apparatus comprising a toroidal shaped casing, a ,multiplicity ol inductance units of diierent frequency characteristics disposed in electrostatically shielded compartments within said casing and spaced from the walls thereof, a switching unit constituted by a cylindrical member extending concentrieally through said toroidal casing, and switching elements projecting through one wall of said cylindrical member and electrically insulated therefrom for establishing selected electrical connection with a particular linductance unit as said cylindrical member is rotatably adjusted Within said toroidal casing.

13, Frequency changing apparatus comprising a supporting frame, a metallic housing carried by said supporting frame comprising a metallic channel shaped structure having a cylin drical aperture extending through the center thereof, a metallic cylindrical member extending through the aperture in said housing and forming the inner wall of the channel shaped struc ture, a plurality of radially extending electrostatic shields disposed in said structure and de v iining compartments in said channel shaped housing, inductance units of different frequency characteristics disposed in said compartments, contact elements extending through said cylindrical member :for establishing electrical connection with selected taps on said inductance units, and

means for rotatably moving said cylindrical member and the contacts projecting therethrough for selecting a particular inductance unit and rendering the same effective whiie electrostatically shielded from others of said inductance units.

14. Frequency changing apparatus comprising a supporting frame, a metallic housing carried by said supporting frame comprising a metallic channel shaped structure having a cylindrical aperture extending through the center thereof, a metallic cylindrical member extending through. the aperture in said housing and forming the inner wall of the channel shaped structure, a plurality of radially extending electrostatic shields disposed in said structure and defining compartments in said channel shaped housing, inductance units of different frequency characteristics disposed in said compartments, an in sulated support disposed within said cylindrical member, contact elements carried by said insulated support and projecting through one wall of said cylindrical member for establishing electrical connection with said inductance units, said radially extending shields each being slotted adjacent said cylindrical member for permitting 'the passage of said contact elements therethrough for establishing electrical connectionwith selected inductance units as said selected member is rotatably adjusted in position within said housing.

LOUIS A. GERHARD. 

